Well where to start.
I bought two 48v 20amp batterys couple a weeks ago. All perfect. But then I seen a video on youtube where you can run a light off your charger input.
Well what did I do only go and try to check the volt output from it with my multimeter and BANG
Damn it anyways. I f'd it up. after paying over 850euro for the two batterys.
Well I tried to charge it but it won't charge. The part you plug the charger was all black. so I cut it off. I took off the shrink wrap but its got a plastic cover and very well wrapped so I went no further. It has a sticker it says LION KING on it.
The wires are all good back to the battery. I'm only getting a reading of 33.3v form the charger input, and 45.6v from the battery output.
What do you guys think I might have done burned out the bms or something else.
I am gutted.

hmm, sounds like you just shorted the pins on the plug and charred the crap out of it.
you will perhaps just need to replace said plug with some soldering, making sure you have polarity right and back yr in buisness.
if you cant find the replacement plug, you might need to use another type rated for same current, on both charger and battery sides
pics will help us let you know what to do

hmm, sounds like you just shorted the pins on the plug and charred the crap out of it.
you will perhaps just need to replace said plug with some soldering, making sure you have polarity right and back yr in buisness.
if you cant find the replacement plug, you might need to use another type rated for same current, on both charger and battery sides
pics will help us let you know what to do

Yeah the connection was badly charred. But I tried a new connection and it still won't charge.
Don't know if to open it up or not, as I've never opened an e battery before.

Here's the pictures of my new batteries. As I said I took off the outer shrink wrap. I'm Afraid to take off inner cover.

Having done this myself, more than once, I can feel your pain but in my case I never ruined anything except my pride.

First off I hate those barrel type charge connectors and chop them off ( carefully) with glee any chance I get and replace with xlr connectors that I like, but they are big.

First rule to never break,...don't touch black and red together, + and -, ever.... really don't do it even for fun,

The first time I was changing the charge plug and shorted it out the fix was just to repair connector and plug into charger and charger reset bms,

Second time, (apparently not a quick learner), It happens really fast you know, this bms had a reset button that had to be pressed to turn it back on after a short. I needed to access bms, locate button, which was look through holes in heat sink plate of bms to locate button and press, my vendor alerted me to button and location to access it,

Having done this myself, more than once, I can feel your pain but in my case I never ruined anything except my pride.

First off I hate those barrel type charge connectors and chop them off ( carefully) with glee any chance I get and replace with xlr connectors that I like, but they are big.

First rule to never break,...don't touch black and red together, + and -, ever.... really don't do it even for fun,

The first time I was changing the charge plug and shorted it out the fix was just to repair connector and plug into charger and charger reset bms,

Second time, (apparently not a quick learner), It happens really fast you know, this bms had a reset button that had to be pressed to turn it back on after a short. I needed to access bms, locate button, which was look through holes in heat sink plate of bms to locate button and press, my vendor alerted me to button and location to access it,

Yeah a lesson to be learned. Its a very bad feeling when you've done it.
Well I took the plunge and opened it up.
I can see that the ends of the wires on the batteries are all burned. But the connection to the BMS is all fine. Thank goodness for that.
That's why I'm getting such a low voltage reading for the charge input.
I was thinking of bring it to the shop were they fix pc's, laptops phones do you's think they would be up for the job.

Here's the pictures of the battery connections, you can see where its black burned at the wire on the batteries.

The good news is they are 18650 cans, not pouches. Pouches need to be compressed a bit. So you can open up the shrink wrapping and inspect if you so wish, but you need to protect them when you wrap them back up. I use Duct Tape and 1/8" particle board.

Didnt read the entire thread, but my first thought was your packs maybe pouches and your hesitation to open them up would be right.

Not sure whats wrong but maybe the bms is broken, or you messed up the charger if you were using it when that happened. I would get on finding out what the problem is. First see where the pack sits right now.

Buy a Digital Multimeter right now, measure the battery itself. You dont want them to sit at minimum voltage for long, nor max voltage.

The good news is they are 18650 cans, not pouches. Pouches need to be compressed a bit. So you can open up the shrink wrapping and inspect if you so wish, but you need to protect them when you wrap them back up. I use Duct Tape and 1/8" particle board.

Didnt read the entire thread, but my first thought was your packs maybe pouches and your hesitation to open them up would be right.

Not sure whats wrong but maybe the bms is broken, or you messed up the charger if you were using it when that happened. I would get on finding out what the problem is. First see where the pack sits right now.

Buy a Digital Multimeter right now, measure the battery itself. You dont want them to sit at minimum voltage for long, nor max voltage.

No wasn't using the charger at the time. I was checking the voltage from the charger input on the battery as I seen a video saying you can run a light from it. What I did was checking it with my volt meter and it made a load bang and burned the connection.
But I've since cut off the connector it was burned black but the wires are all good.
I am getting a reading of 45.6 volts from the output and 33.3 from the charger input.
I cleaned all the wires that are soldered to the batteries and they are all good.
You could be right the bms might be a goner. How do I check this? And if its broke can I get the same one again.

So 13series of parallel groups. Start at the neg end or #1 check voltage and write down on paper then go to #2 write down.
1. 3.65v
2. 3.91 v
3. 4.10v

13. Xxx voltage.
Let us know the state of charge if your battery. It looks like a benign block of batteries it is not it's full of intense energy that can cause a fire be careful no toy. A little 9v battery can start a fire what can a 54v battery do ?

Jeez what a poorly constructed battery.... 850eu
Sorry to say it, but it'd pay to fix it up a bit while you've got it open.
I'd chuck some insulation under those sense wires, glue the cells together so they can't move, add at least two more series connections per parallel group to spread the power across the cells (more) evenly and prevent heat in those two bits of nickel, and I'd also parallel some extra power outputs to the existing ones, again to help spread the load.
Thatd go a long way to ensuring your battery lasts as long as it can.

The problem will be with the BMS. The charge control circuit is open, since you aren't seeing pack voltage on the charge input. Sometimes unplugging the BMS (as I see in the picutre) and plugging it back in might reset things. If you still don't see full pack voltage on the charge wires, then the BMS is likely toast and needs to be replaced or repaired. The BMS may actually be repairable if it just blew a trace.

So 13series of parallel groups. Start at the neg end or #1 check voltage and write down on paper then go to #2 write down.
1. 3.65v
2. 3.91 v
3. 4.10v

13. Xxx voltage.
Let us know the state of charge if your battery. It looks like a benign block of batteries it is not it's full of intense energy that can cause a fire be careful no toy. A little 9v battery can start a fire what can a 54v battery do ?

I looked at some videos on youtube on how to do this so I'll give it a try in the morning. Your scaring me about it been a fire hazard.

Jeez what a poorly constructed battery.... 850eu
Sorry to say it, but it'd pay to fix it up a bit while you've got it open.
I'd chuck some insulation under those sense wires, glue the cells together so they can't move, add at least two more series connections per parallel group to spread the power across the cells (more) evenly and prevent heat in those two bits of nickel, and I'd also parallel some extra power outputs to the existing ones, again to help spread the load.
Thatd go a long way to ensuring your battery lasts as long as it can.

No it was 850 euro for two batteries. I know what your saying about upgrading the battery, but I wouldn't have a clue how to do this.
But thanks for helping me to get it to work better. cheers.

The problem will be with the BMS. The charge control circuit is open, since you aren't seeing pack voltage on the charge input. Sometimes unplugging the BMS (as I see in the picutre) and plugging it back in might reset things. If you still don't see full pack voltage on the charge wires, then the BMS is likely toast and needs to be replaced or repaired. The BMS may actually be repairable if it just blew a trace.

Hi
Yeah I plugged it back in and still the same, How do I check the bms. And were do I get one for this, dose it have to be the very same?
thanks Oh yeah whats a trace?

Hi
Yeah I plugged it back in and still the same, How do I check the bms. And were do I get one for this, dose it have to be the very same?
thanks Oh yeah whats a trace?

You want to inspect the circuit board on the bottom. Traces are the copper lines printed on the circuit board. It's possible one of them burned up, which should be pretty obvious when you see it. Just look for anything burnt up.

You may need to inspect between the metal plate and the board. To do this, I really recommend disconnecting the main red wire going to the pack first to make sure nothing can short out. If there is a separate black wire for the charger input, you want to try tracing the path it takes on the board.

I'm afraid to test the wire's from the batteries, with the multi meter.
If I do try to test them what do I do? is it start at the black wire two by two and move all the way to the red wire? on the block I plug out from the bms.

There is a guy that works in maintenance where I work. He dose all electrical work.

So 13series of parallel groups. Start at the neg end or #1 check voltage and write down on paper then go to #2 write down.
1. 3.65v
2. 3.91 v
3. 4.10v

13. Xxx voltage.
Let us know the state of charge if your battery. It looks like a benign block of batteries it is not it's full of intense energy that can cause a fire be careful no toy. A little 9v battery can start a fire what can a 54v battery do ?

Well I done the test and the reading I got was 3.5v from start of neg to live on other end. Is this normal?

I took photos of the inside of the bms hope you's can see but there is some sort of a scrape or something in there. There is a L letter just before it. not sure if this is the problem.

Yiu should write the voltages down on paper. So you can compare the next time you checked the voltages all 13 written on a piece of paper. I'm just trying to tell you there's a lot of stored energy in that benign looking box of battery cells.

Yiu should write the voltages down on paper. So you can compare the next time you checked the voltages all 13 written on a piece of paper. I'm just trying to tell you there's a lot of stored energy in that benign looking box of battery cells.

Yes if ALL are above 3.5v. Yes. Low voltage or zero is closer to 2.8v as zero. It depends on the cell I wouldn't go below 3.0v ever. It when you go lvc and one string bottoms out first because of lower capacity other strings may be filled up to the top as far as water in the glass but when one runs out of capacity the whole battery is not 13s anymore . Write it down helps you more than it helps me.